Session getting terminated while recording the script

While recording an application in web(HTTP/HTML) mode, we faced the problem of the session getting terminated during the recording.
The occurence of this problem was random. After proceeding a few steps(clicking different tabs and buttons)with the recording we faced this issue.
The following observations were made:
1> The http in the request was changed to https.
2> While browsing the application manually, this problem did not occur.
3> Loadrunner 8.1 was used for recording.